1. Field of the Invention
The present invention relates to a discharging valve assembly of a reciprocating compressor, and more particularly, to a discharging valve assembly of a reciprocating compressor capable of improving discharging efficiency of gas compressed in a cylinder and discharged as well as minimizing noise generation.
2. Description of the Background Art
In general, a reciprocating compressor is an apparatus for sucking and compressing refrigerant gas while a piston linearly and reciprocally moves in a cylinder. A reciprocating compressor is largely divided into two methods according to a driving mechanism. One is a method of converting a rotational movement into a linearly reciprocating movement, and transmitting the linearly reciprocating movement to a piston. The other one is a method of directly transmitting a linearly reciprocating movement of a motor to a piston.
FIG. 1 is a view showing one example of a reciprocating compressor. As shown therein, the reciprocating compressor includes a casing 10 coupled with a gas suction pipe 1 and with a gas discharging pipe 2; a front frame 20 and a middle frame 30 installed at a certain interval therebetween in the casing 10, and elastically supported by springs (not shown); a driving motor 40 mounted between the front frame 20 and the middle frame 30, and generating a linearly reciprocating driving force; a cylinder 50 inserted in the front frame 20; a piston 60 received the driving force of the driving motor 40, and thus linearly and reciprocally moved in the cylinder 50; a rear frame 70 covering the piston 60; a resonant spring 80 elastically supporting the piston 60 and inducing a resonant movement of the piston 60; a suction valve 90 coupled with an end surface of the piston 60, and controlling flow of gas introduced into the cylinder 50 according to linearly reciprocating movement of the piston 60; and a discharging valve assembly 100 installed one side of the cylinder 50, and controlling discharge of gas compressed in the cylinder 50 according to the linearly reciprocating movement of the piston 60.
The driving motor 40 includes an outer stator 41 mounted between the front frame 20 and the middle frame 30; an inner stator 42 inserted in the outer stator 41, and mounted at the front frame 20; a winding coil 43 coupled with the outer stator 41; and a movable unit 44 inserted between the outer stator 41 and the inner stator 42 so as to be linearly movable. The movable unit 44 includes a cylindrical holder 45 and a plurality of magnets 46 coupled with the holder 45, and the holder 45 is connected with the piston 60.
The discharging valve assembly 100 includes a discharging cover 101 for covering an inner space of the cylinder 50; a discharging valve 102 positioned in the discharging cover 101, and opening/closing the inner space of the cylinder; and a valve spring 103 elastically supporting the discharging valve 102. The gas discharging pipe is connected to the discharging cover.
items 104, and 105, which are not explained above, are a coupling bolt and a nut, respectively.
Operations of the reciprocating compressor as above will now be described.
First, when power is applied to the compressor, a linearly reciprocating driving force is generated at the driving motor 40, and thus the movable unit 44 of the driving motor is linearly and reciprocally moved. The linearly reciprocating movement of the movable unit 44 is transmitted to the piston 60, and thus the piston 60 is linearly and reciprocally moved at the inner space of the cylinder 50. According to the linearly reciprocating movement of the piston 60 at the inner space of the cylinder 50, while the suction valve 90 and the discharging valve assembly 100 open/close a gas channel by a pressure difference generated in the cylinder 59, gas is sucked into the cylinder 50, compressed, and discharged. The gas compressed at and discharged from the inner space of the cylinder 50 is discharged outside of the casing 10 by way of the inside of a discharging cover 101 and through the gas discharging pipe 2. This process above is continuously repeated so that gas can be compressed.
In the reciprocating compressor, a degree of noise generation is affected by operations of the discharging valve assembly 100 for discharging gas compressed by the linearly reciprocating movement of the piston 50. In addition, by operations of the discharging valve 100, flow resistance of discharged gas is affected, and thus a discharge amount of gas. Accordingly, a study of the discharging valve assembly 100 is an important factor to increasing reliability and efficiency, and so many studies are in progress.
FIG. 2 is view showing one example of a conventional construction of a discharging valve assembly for the reciprocating compressor. As shown therein, the discharging valve assembly for the conventional reciprocating compressor includes a discharging cover 110 for covering the inner space of the cylinder 50; a discharging valve 120 inserted in the discharging cover 110, and opening/closing the inner space of the cylinder 50; and a valve spring 130 for elastically supporting the discharging valve 120. The discharging cover 110 is formed in a cap shape having a certain thickness. That is, the discharging cover 110 is provided with a fixing unit 112 bent and extended at one side of a cylindrical portion 111 having a certain length and an outer diameter, and coupled with the front frame 20; a discharging hole 113 coupled with the gas discharging pipe 2 at one side of the cylindrical portion 111; and a supporting wall portion 115 formed at the other side of the cylindrical portion 111, covering the cylindrical portion 111. The supporting wall portion 115 vertically meets the cylindrical portion 111.
The discharging valve 120 is provided with a spring coupling portion 122 protruded at one side of a hemisphere 121, and a round compression plane 123 closing the inner space of the cylinder 50, and formed at the other side of the body portion 121.
The valve spring 130 is a coil spring having a certain length.
One side of the valve spring 130 is coupled with the spring coupling portion 122 of the discharging valve, and the other side thereof is contactedly supported by an inner surface 114 of the supporting wall portion of the discharging cover 110. At this time, the compression plane 123 of the discharging valve is in contact with a contact surface S1, an end surface of the cylinder 50. The inner surface 114 of the supporting wall portion of the discharging cover being in contact with the valve spring 130, is a plane, which is in parallel with the contact surface S1 of the cylinder 50 being in contact with the compression plane 123 of the discharging valve.
Operations of a discharging valve assembly for the conventional reciprocating compressor as above will now be described in detail.
As shown in FIG. 3, when the piston 60 moves from a top dead point to a bottom dead point, the compression plane 123 of the discharging valve is adhered to the contact surface S1 of the cylinder 50 by a pressure difference at the inner surface of the cylinder 50. Simultaneously with this adhesion, the suction valve 90 is opened, and thus gas is introduced into the inner space of the cylinder 50 through a channel formed in the piston 60.
As shown in FIG. 4, when the piston 60 moves from a bottom dead potion to a top dead point, the suction valve 90 closes the gas channel of the piston 60, and thus gas sucked into the inner space of the cylinder 50 is gradually compressed. When the gas is in a predetermined compression state, the discharging valve 120 supported at the valve spring 130 is opened, and thus the compressed gas is discharged. This process is continuously repeated so that gas can be compressed.
In the discharging valve assembly as above, shapes of the inner space of the cylinder 50 for discharging gas and a discharging valve 90 for opening/closing the inner space of the cylinder 50 are formed so as to have a maximum discharging area. For this reason, flow of discharged gas is smooth, and efficiency is excellent since a great amount of gas is discharged at a time.
However, elastic stiffness of the valve spring 130 elastically supporting the discharging valve 120 is designed to be weak in order to make a movement of the discharging valve 120 smooth. So, as the discharging valve 120 is moved, the moving width thereof becomes greater, and thus an impulse generated when the valve 120 comes in contact with the cylinder 50 is increased whereby a valve contact noise of a high frequency band is greatly generated.